Microbial contamination due to sewage discharge and dumping of solid waste has affected the water quality in five river basins in Kerala, highlighting the need for stricter monitoring and management of water resources.
The findings have been published by the Centre for Water Resources Development and Management (CWRDM) based on a study of the Mogral, Chittari and Shiriya river basins in Kasaragod, the Pambar river basin in Idukki, and the Bhavani river basin at Attappady. The study was carried out as part of the Environmental Monitoring Programme on Water Quality taken up by the Kerala State Council for Science, Technology and Environment.
The survey revealed that 67% of the water samples collected from the Mogral river basin were of poor quality while 23% were of marginal quality. The majority of the surface water samples from the Mogral could be used for drinking only after conventional treatment and disinfection. Sewage input was detected at the Mogral kadavu while solid waste dumping was identified as a major problem near the mouth of the river.
All the water samples collected from the Pambar river basin were found to be of marginal quality indicating that the water could be used for drinking only after disinfection. Maximum microbial contamination was reported in the pre-monsoon season.
Analysis of the samples from the Chittari basin revealed that 25% were of poor quality and the rest had marginal quality. The percentage of E.coli contamination was found to be high in the monsoon season. The downstream areas were more polluted, with Madiyan thodu recorded as the most polluted location.
The water quality in the Bhavani river basin ranged from good and fair to marginal. The maximum microbial contamination was reported in the pre-monsoon season. A high degree of organic degradation was reported from the Kakkapady site.
Analysis of the surface water samples collected from the Shiriya river basin showed that 20% were of poor quality and 80% of marginal quality. Maximum microbial contamination was in the pre-monsoon season. The area near the Angadi Mugar and Adkasthala bridges were the most polluted locations. Up to 80% of the groundwater samples were also bacteriologically contaminated during the pre-monsoon season.
The concentration of organochlorine pesticides was found to be below detection limit in all the five river basins.
